The Research On The Coupling Performance In Various Fields Of Pvc Sheet With Defects

In a great degree and range, high-quality polymer materials are used as the substitutes of metal in various industries, as they are in low cost and easy to manufacture and get. Also, the tendency is growing and developing. Today, science develops quickly, and there are statistics which show that the use of high polymer materials have exceeded the use of metal in volume. There are micro-defects (inclusions, microbores, micro-crack, etc) existed or formed in the process of manufacturing, preparing, storage, transportation and using of both high polymer materials and metal materials, therefore we call them rheological bodies with defects. Those kinds of micro-defects expand gradually because of generalized external load, and they present rheological properties (such as visco-elastic, visco-plastic, etc.) which can cause damage and rupture. The process of this kind of damage not only contains the problem of geometrical non-linear in the deformation of material and the expansion of micro-crack, but also the problem of physical non-linear of thermomechanical coupling in irreversible deformation. In the damage process of rheological damage area, a temperature gradient comes with the dissipation of energy, and the temperature falls in the elastic process in the initial process of tension. As to know the above dissipation theoretically and the rule of the change of temperature field, we have to analyze them in the theory of micro-molecular and macroscopic phenomenological method.Based on the nonequilibrium irreversible thermomechanics and the theory of continuum mechanics, this paper gives the control equation in the deformation area of polymers, which includes the equation of entropy production. Then the paper explains the mechanism of the cooling phenomenon during elastic deformation of polymers theoretically and generally. The cooling phenomenon can be measured by the orientation degree, derived from theories of molecular orientation and conformation.In the third chapter, considering rate-dependency and the distribution of defects, the temperature fields on the surface of high polymer specimen are measured by infrared thermal imaging. Derived from the experiments, the evolution rule of defects and the dissipation law of temperature are achieved, and the calculation method about the heat productivity is introduced.It is very important for their theoretical and industrial significance that the work mentioned above for founding the failure criterion and the fracture theory, for estimating the longevity of high polymer material under complex working environment; it is also important for using the materials correctly and designing new materials, for preventing accidents and assuring the security in producing process and developing the national economy.